Form stripping tool and sealing cap



May 2, 1967 5. J. KROLL FORM STRIFPING TOOL AND SEALING CAP Filed Aug. 5, 1964 2 2 6 3 6 4 a m 4 4 e 2 w 2 H m Bi F M a: A: Em 0 .71 1 3F 2 h I z a m an T Y: 0 M V. 3

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L L 0 R K J- Y E L N M S INVENTOR ATTORNEY United States Patent O 3,316,607 FORM STRIlPlNG T001. AND SEALING CAP Stanley J. Krol], 3420 Urbana 5., Laurel, Md. 20810 Filed Aug. 5, 1964, set. No. 387,564 5 Claims. (Cl. -126) This invention relates generally to tools for loosening and facilitating the removal of concrete form elements. More particularly, it relates toa tool for facilitating rapid stripping of decking, keyways, steel pans, and other form elements from a finished concrete structure, with a minimum of damage to both the concrete and to the form elements, and to a sealing cap for use with said stripping tool.

In the construction of concrete structures it is necessary to first build a form, into which a concrete mixture is then poured and allowed to harden. A typical construction job will require the use of various types of form elements, all of which must usually be removed after the concrete has set. In the past, the removal of such form elements has often been a diflicult and time consuming procedure, and has frequently resulted in damage to the concrete structure and to the form elements. The form stripping tool of the present invention is designed to greatly diminish the time required to strip form elements, and to minimize the possibility of damage to such form elements and to the concrete structure.

The stripping tool of the invention includes an elongated body having a threaded axial bore therethrough, and which is provided with an annular flange at its upper end. A threaded shaft is received within the threaded bore and is surmounted by a swivel head, the upper end of the body having a recess therein for receiving the swivel head when the shaft is in a retracted position. The lower end of the shaft has a hexagonal head thereon, and the lower end of the body is provided with a pair of diametrically opposed flats, the hexagonal head and the flats both being provided to receive wrenches for operating the tool.

In use, a form element with which the stripping tool is to be utilized is provided with a hole having a diameter slightly greater than that of the tools body. The tool body is inserted through the hole from the concrete-receiving side of the form element, until the annular flange thereon engages said element. The threaded shaft is re tracted at this point, so that the swivel head is received within the recess in the upper end of the tool body.

If wet concrete were to be poured directly on the upper, unprotected end of the stripping tool, it is probable that a portion thereof would flow between the swivel head and the walls of the recess within which it is received, and then between the threads carried within the body bore and the threads on the shaft. Any concrete thus flowing between the threads could easily freeze them, thus preventing proper operation of the tool. To avoid this happening, and for other reasons, a cup-shaped cap member is provided.

The cap member of the invention includes a radial end wall having a cylindrical wall extending therefrom, the inner diameter of the cylindrical wall being slightly greater than the external diameter of the annular flange on the stripping tool body. The cap is installed over said flange before pouring the concrete mixture, and functions to prevent the entry of foreign substances in the interior of the tool.

Depending upon the particular configuration of the structure to be built from concrete, a form element can assume several configurations. When pouring a floor or a vertical wall, it is common practice to employ large sheets of fairly thick plywood as a decking, or surface, onto which the concrete is poured. The sheets of decking are first braced in position by shoring or framing, and the concrete mixture is then poured thereon. After the concrete has hardened, the wood decking sheets must be removed, preferably with as little damage as possible to them and to the concrete.

In the past a common method for removing decking has been to first break or chisel out one corner of a sheet or piece of a sheet, after which a pry bar is employed to free the entire sheet. This process is time consuming, and frequently results in either destruction of a sheet of decking, or in causing such extensive damage thereto that it must be repaired before it can be again utilized.

With the present invention, the stripping tool is first installed before pouring concrete into the form, and a cap member is placed thereon. If the material of the form element is wood, the cap member is provided with a plurality of teeth which are driven into the wood to hold the tool and the cap member in place during pouring, even in the presence of vibrators, tampers and other instruments utilized to help distribute and settle the concrete.

After the concrete has set, a wrench is applied to the hexagonal head on the lower end of the threaded shaft, and the shaft is turned relative to the body in a direction to move the swivel head vertically out of its recess. If necessary to prevent the body from turning, a second wrench can be applied to the opposed flats on said body. As turning of the shaft progresses, the swivel head and the flange move apart relatively to thereby move the portion of the form element around the tool away from the concrete.

When the swivel head first moves vertically, the cap member is freed from the form element. Thereafter, the swivel head carries the cap therewith, and functions in two principal ways to facilitate operation of the invention. First, the swivel head, by standing still relative to the concrete while the shaft is rotating, minimizes any tendency for the shaft to dig into the fresh concrete. Second, the swivel head corrects for any misalignment of mechanical forces occurring as the body of the tool tilts during operation of the threaded shaft.

After the shaft has been threaded several inches into the body, the form element will be freed sufliciently from the concrete structure to make final removal thereof an easy task. The stripping tool of the invention is used in a similar manner with various types of form elements, such as keyways, steel pans, decking, and the like, all as will be described hereinafter.

It is an object of the present invention to provide a stripping tool constructed to facilitate the removal of form elements from a concrete structure in a minimum of time, and with a minimum of damage to both the form elements and to the fresh concrete.

Another object is to provide a stripping tool which is self-contained, and which can be utilized with a variety of form elements.

A further object is to provide a stripping tool that is easy to install and operate, and that is relatively economical to construct.

It is also an object to provide a cap that can be utilized to close a hole in a form element, constructed to be easily installed and to remain fixed in position.

Still another object is to provide a cap for a stripping tool, constructed to seal the tool against the undesired entry of water or concrete mixture, and that is relatively economical to construct.

Other objects and many of the attendant advantages of the invention will become more readily apparent from the following detailed description when taken in connection with the accompanying drawings, wherein:

FIG. 1 is a fragmentary view, partially in section, showing a first embodiment of the stripping tool and cap member of the invention installed in a sheet of plywood decking with concrete poured thereon;

FIG; 2 is an enlarged, exploded elevational View of the stripping tool and cap member of FIG. 1;

FIG. 3 is a fragmentary, vertical sectional view of the stripping tool of FIG. 2, taken generally along the line 3-3 of FIG. 2;

FIG. 4 is an enlarged fragmentary view similar to FIG; 1, but showing the stripping tool and cap member after the threaded shaft has been operated;

FIG. 5 is a fragmentary view, partially in section, showing the strippnig tool and cap member of FIG; 1 employed with a keyway form element; I

FIG. 6 is a fragmentary view, partially in section, showing a second embodiment of the invention, constructed for use with a steel pan form element;

FIG. 7 is an elevational view of the cap member of FIG. 6; and

FIG. 8 is an enlarged, fragmentary elevational view, partially in section, of a modified flange and cap member, preferred for those applications where it is desired to firm- 1y secure the stripping tool in position relative to a wood form element.

Referring now to the drawings, a first embodiment of the stripping tool of the invention is shown at 2 in FIGS. 1-5, said tool 2 including a body 4 terminating at its upper end in an annular, circular flange 6. The body 4 tapers inwardly from the upper to the lower end thereof, say at an angle of taper of about 5 degrees, and is provided with an axial bore 8 which extends therethrough.

The bore 8 terminates at its upper end in an enlarged recess 10, comprising a cylindrical upper portion 12 and a tapered lower portion 14. The remainder of the bore 8 below the recess has threads 18 formed therein, which preferably are of a type which will transmit a large resultant force relative to the amount of torque exerted on the body carrying the thread; it has been found that an acme thread form is suitable, although other thread forms might also be utilized. The lower end of the body 4 has a pair of diametrically opposed flats 20 formed thereon, to provide wrench engaging surfaces.

Received within the bore 8 is a shaft 22, having threads 24 thereon of a size and configuration to mesh with the threads 18. The shaft 22 terminates at its upper end in an integral, spherical ball 26, and has a hexagonal head 28 on its lower end. The length of the shaft 22 above the hexagonal head 28 is substantially greater than the height of the body 4, whereby to allow the upper end thereof to project a substantial distance above the body 4 when said shaft is threaded upwardly therein.

Fitted on the ball 26 is a swivel head 30, having a spherical recess in the underside thereof of a size to receive said ball 26, the mouth of said recess being peened over to affix said swivel head to the shaft 22. The swivel head 30 is of a size to be received within the recess 10, and is arranged so that the top surface thereof will be flush with the top surface of the flange 6 when said swivel head is seated within said recess.

Referring now to FIG. 1, there is illustrated a typical form structure for use in pouring a concrete floor 32. In FIG. 1, the floor 32 is disposed to rest upon a wall of blocks 34, and shoring 36 supports plywood decking sheets 38 upon which the concrete 32 is poured. The plywood decking sheets 38 typically will be rectangular, and will have a thickness of about /8 inch. Normally, a plurality thereof will be utilized to provide a large deck area upon which to pour concrete.

After the concrete has set, it is necessary to remove both the shoring members 36 and the plywood decking sheets 38. While the shoring members usually can be easily removed, considerable difliculty is typically encountered in removing the sheets 38. This occurs because the sheets often become wedged in position, and because they tend to adhere to the concrete 32.

Form decking sheets such as the plywood sheets 38 are conventionally removed by first working with hammer, chisel and pry bar on one corner thereof, until an edge Cal has been pried down from the concrete. This process usually causes damage to the plywood, requiring repair before the sheet can again be utilized. After an edge has been freed, a pry bar is worked under the sheet, and the whole of the sheet is then worked loose, the entire stripping operation frequently taking one-half hour or more. The present invention makes this conventional stripping process obsolete in most instances, and makes possible the stripping of a form element in far less time than was heretofore possible.

When utilizing the stripping tool 2 of the present inven tion, a hole 40 is first made in each sheet 38, preferably near a corner thereof The hole 40 preferably has a diameter just slightly greater than the diameter of the body 4 adjacent the flange 6. After the plywood decking sheets 38 have been installed and supported by the shoring members 36, and just before pouring, a stripping tool 2 is placed in each of the holes 40, with the shaft 22 pointing downwardly, and with the undersurface of the flange 6 in engagement with the concrete-receiving surface of its associated sheet 38.

Because entry of wet concrete mixture between the threads 18 and 24 could easily jam said threads and prevent operation of the stripping tool 2, it is necessary to prevent such entry. For this purpose, a cap member 42 is provided, said cap including a circular end plate 44 having a cylindrical rim 46 secured thereto. The inner diameter of the rim 46 is just slightly greater than the external diameter of the flange 6, and the axial length of said rim measured between the inner surface of the end plate 44 and the lower edge 48 thereof is a few thousandths of an inch greater than the height of the flange 6.

The cylindrical rim 46 to the cap member 42 is also provided with a plurality of circumferentially spaced, generally triangular teeth 50, which project downwardly from the edge 48. While the number of teeth 50 can be varied, it has been found that from five to eight will provide the desired results.

In use, the cap member 42 is placed over the flange 6 after the stripping tool 2 has been inserted into the hole 40. The cap member 42 is then driven downwardly, until the inner surface of the end plate 44 rests on the top surface of the flange 6. This results in the teeth 50 being imbedded in the plywood material of the decking sheet 38, which teeth then function to hold both the cap member and the stripping tool 2 in position against accidental displacement such as might be caused by a workman accidently striking them, or by vibrators and other compacting instruments inserted into the concrete mixture.

When the cap member 42 is driven downwardly, the lower edge 48 on the rim 46, because said rim has an axial length greater than the height of the flange 6, will also bite into the plywood sheet 38. This increases the effectiveness of the sealing action provided by the cap member 42, and thus further insures against accidental leakage of cement mixture between the threads 18 and 24. After caps have been placed on the flanges 6 of all the stripping tools 2 utilized in the form, pouring the concrete commences.

After the concrete has set, the shoring members 36 are first removed. A wrench is then applied to the head 28 on the lower end of the shaft 22 of the stripping tool 2, and said shaft is threaded upwardly into the tool body 4. If the tool body 4 tends to turn, then a second Wrench is engaged with the flats 20 on the lower end thereof. As turning of the shaft 22 progresses, the swivel head 30 emerges from the recess 10 and presses against the concrete 32. This in turn causes the lower surface of the flange 6 to engage the sheet 38, urging said sheet away from the concrete 32.

Referring to FIG. 4, the stripping tool 2 is shown midway through its operaton. As the swivel head 30 moves upwardly, it carries the cap member 42 therewith. When the portion of the sheet 38 in which the tool 2 is mounted has moved downwardly away from the concrete 32, and

while the remainder of the sheet remains in contact with said concrete, the central axis of the shaft 22 will no longer remain perpendicular to the lower surface of the concrete 32. However, the swivel head 30 compensates for such misalignment, and causes the torque forces applied to the shaft 22 to be directed in a manner to separate the sheet 38 from the concrete 32, and so as not to place undue strain on the tool 2. In addition, the swivel head 30, because it can stand still relative to the concrete 32 while the shaft 20 rotates, protects the fresh concrete 32 against damage that might result from a rotating member.

After the shaft 22 has been threaded into the body 4, the portion of the plywood decking sheet 38 in which the stripping tool 2 is mounted will be spaced sufiiciently from the concrete 32 to permit easy grasping thereof, whereby final removal can be easily accomplished. The operation of the stripping tool 2 takes but a few minutes, and causes no damage to the plywood sheets 38. Thus, said sheets can immediately be reused, and the life thereof is substantially prolonged. Further, because the use of chisels and ply bars is largely eliminated, damage to the fresh concrete 32 is minimized in most applications.

After the sheet 38 has been removed from the concrete 32, the stripping tool 2 is likewise removed. The cap member 42 can then be removed from its recess 52 within the concrete by grasping it with a pliers, or other suitable tool. The recess 52 can then be filled with grout, if a smooth concrete finish is desired. If a hole 40 is not to be subsequently used in a sheet 38, it can easily be covered by a metal plate to render it ineffective. Usually, the cap members 42 become so distorted in use that reuse thereof is not possible.

While the dimensions of the stripping tool 2 can be suitably chosen for a particular application, it has been found that for typical use a body tool 4 having an overall axial length of about 2 inches is satisfactory. For such a body 4, the flange 6 should have a diameter of about 1.621 inches, and a thickness of about 0.218 inch. The cap member 42 for use with such a flange 6 should have a rim 46 having an axial length of about 0.238 inch. The cap members 42 preferably are made from a relatively stiff, thin metal which will not rust, such as galvanized steel.

The stripping tool 2 and the cap member 42 can be utilized with numerous other form elements than the decking sheets 38. For example, they can be utilized with a keyway form structure such as that shown in FIG. 5. Keyway form elements are normally employed to form rectangular recesses in a finished concrete structure to receive stel beams, reinforced mezzanines, electrical outlet boxes, fuse boxes, and the like. In the past, the removal of the components of such a keyway form has been most difiicult, and often results in severe damage to the finished concrete.

Referring to FIG. 5, a pair of decking sheets 54 are shown supported in spaced, parallel relationship. Secured to one of the sheets 54 is a keyway form 56, comprising side members 58 and a bottom plate 60, all of which are normally nailed or otherwise secured in position. Before concrete is poured into the form, stripping tools 2 and cap members 42 are installed in the side members 58 and the bottom plate 60. Thus, after the concrete 62 which is poured into the form has set, the elements of the keyway form 56 can be easily removed merely by operating the stripping tools 2.

Another type of form element in widespread use today is the steel pan, such a pan being shown at 64 in FIG. 6, resting on plywood decking 65. Each pan 64 normally includes tapered side walls 66 formed integrally with a bottom wall 68, and having a rim 70 around their outer edges. Commonly, pans such as the pan 64 are removed from a concrete structure such as that shown at 72 by air pressure. However, occasionally air compressors fail in the field, and it then becomes necessary to remove the pans 64 in other ways.

In FIG. 6, the pan 64 is provided with a central opening 74 in the bottom plate 68, within which is received the body 4 of a stripping tool 2. A cap member 42 is received over the flange on the tool 2, said cap member 42 being shown in FIG. 7. The pan 64 is reinforced by a collar 69 extending around the opening 74, and by webs 71 extending outwardly from the collar 69.

The cap 42 is similar to the cap member 42, except that it is not provided with teeth corresponding to the teeth 50. Such teeth are not usable with the steel material of the pan 64, and hence are not needed. If desired, the stripping tool 2 employed with the steel pan 64 can be welded thereto, to insure that it will not become displaced. The interior of the pan 64 is reinforced by the collar 69 and the Webs 71 to insure that it will not become deformed when the tool 2 is operated to remove the pan 64 from the concrete structure 72; in some instances, it may be possible to eliminate the webs 71 and the collar 69 if the pan is sufficiently strong.

From the illustrations given, it is readily seen that the stripping tool 2 can be easily utilized with various types of concrete form elements. In each instance it can be operated in a similar manner to rapidly remove the form element, without causing damage to the fresh concrete.

When a stripping tool 2 is installed in a vertical ply- Wood decking sheet, or in a horizontal decking sheet where the possibility of accidental displacement is high, it is desirable to more firmly secure it in position. A modified stripping tool 2 and cap member 42" are shown in FIG. 8 which are particularly adapted for this purpose.

Referring to FIG. 8, the stripping tool 2' is identical to the tool 2, except that the flange 6' thereof is provided with a plurality of circumferentially spaced, axially directed through bores 76, say three thereof spaced 120 degrees apart. The tool 2 is installed in a bore 78 provided in a sheet of plywood decking 79, with the flange 6 in engagement with said decking.

The cap member 42 includes a circular bottom wall 80 and a rim 82, the latter having a slightly greater axial length than the thickness of the flange 6'. The bottom wall 80 is provided with a plurality of bores 84, one in alignment with each of the bores 76. A pointed pin 86 is secured within each of the bores 84, each of said pins 86 having a reduced diameter upper end por tion 88 of a diameter just slightly less than that of the bores 84. The pin portion 88 are passed through the openings 84, and the upper ends of said pins are then peened over to secure them in position.

The lower portions of the pins 86 have diameters just slightly less than that of the bores 76, and are receivable therethrough. The pins 86 have lengths somewhat less than the combined thicknesses of the flange 6 and the plywood sheeting 79. In use, after the tool 2' is installed, the cap member 42" is placed thereon, with the pins 86 received in the bores 76. The cap member 42" is then driven downwardly, the pins 86 being guided by the bores 76. After the lower ends of the pins 86 have been driven into the plywood material of the sheet 79 the stripping tool 2', as well as the cap member 42", will be firmly secured in position.

The cap members 42 and 42 are also useful apart from the stripping tool to close a hole in a sheet of plywood decking or the like. In this instance the means for fastening the caps in position, that is, the teeth 50 or the pins 86, are employed to secure their respective caps over a hole, the bottom edges of the caps again being driven into the plywood to provide a good circumferential seal.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. In a form structure incorporating a form element having a bore therethrough, a tool freely receivable within and freely removable from said form element bore and adapted for stripping said form element from a cast structure, comprising: a body receivable within said through bore, and having a threaded bore extending axially therethrough; an annular flange on the upper end of said body, said flange being substantially larger in diameter than said through bore in said form element; a threaded shaft received within said threaded bore, and having a length substantially greater than that of said body; a head mounted for universal swivel movement on the upper end of said shaft; and means on the lower ends of said body and said shaft defining wrench-engagement surfaces.

2. A device for stripping a form element from a cast structure, said form element having a bore extending therethrough, comprising, in combination: a tool, said tool including: a body having a threaded bore extending axially therethrough, said body being receivable within a through bore provided in a form element in which said tool is mounted; an annular flange on the upper end of said body, said flange having a diameter greater than that of a through bore in a form element within which said body is received; a threaded shaft received within said threaded bore, and having an axial length greater than that of said body; and a head mounted for swivel movement on the upper end of said shaft; and a cap member receivable on the upper end of said tool, said cap member including: a radial end wall; and a cylindrical rim secured to said end wall, and having an inner diameter slightly greater than that of said annular flange.

3. In a form structure incorporating a form element having a bore therethrough, a device for stripping said form element from a cast structure, comprising, in combination: a tool, said tool including: a body receivable within said bore in said form element, and having a threaded bore extending axially therethrough, said body also including a recess in the upper end thereof about the upper end of said threaded bore; an annular flange on the upper end of said body, said flange having a diameter greater than that of said bore in said form element, and the top surface of said annular flange being coextensive with the top end surface of said body; a threaded shaft received within and of greater length than said threaded bore; a head mounted for swivel movement on the upper end of said shaft, and receivable within said recess so that the top end face thereof does not protrude above the top end face of said body; and means on the lower ends of said body and said shaft defining wrench-engagement surfaces; and a cap member receivable on said annular flange, said cap member including: an end plate; and a cylindrical rim secured to said end plate, and having an internal diameter slightly greater than that of said annular flange.

4. A device as recited in claim 3, including additionally means on said cap member engageable with said form element for fastening said cap member and said tool thereto.

5. A cap member for reception on the upper end of a form stripping tool to seal said tool against the entry of moisture and to fasten said tool in a mounted position, said tool including an annular flange on the upper end thereof having a plurality of axially extending bores therethrough, said cap member comprising: an end plate; a cylindrical rim secured to said end plate, and having a diameter slightly greater than that of the annular flange on a tool on which it is to be mounted; and means attached to said cap member for fastening it to a form element in which a tool with which the cap member is employed is mounted, said means comprising: a plurality of circumferentially spaced, axially extending pins secured at their upper ends to said end plate and arranged to be received through said axial bores in said annular flange, said pins having an axial length substantially greater than both the length of said rim and the thick ness of said annular flange,

References Cited by the Examiner UNITED STATES PATENTS 370,774 10/1887 Fuller 287-91 1,799,697 4/1931 Moody 25-120 2,360,250 10/ 1944 Mallard 249-66 2,713,710 7/ 1955 Holland 25-120 3,163,910 1/1965 Greene 25-120 0 I. SPENCER OVERHOLSER, Primary Examiner.

G. A. KAP, R. D. BALDWIN, Assistant Examiners. 

1. IN A FORM STRUCTURE INCORPORATING A FORM ELEMENT HAVING A BORE THERETHROUGH, A TOOL FREELY RECEIVABLE WITH IN AND FREELY REMOVABLE FROM SAID FORM ELEMENT BORE AND ADAPTED FOR STRIPPING SAID FORM ELEMENT FROM A CAST STRUCTURE, COMPRISING: A BODY RECEIVABLE WITHIN SAID THROUGH BORE, AND HAVING A THREADED BORE EXTENDING AXIALLY THERETHROUGH; AN ANNULAR FLANGE ON THE UPPER END OF SAID BODY, SAID FLANGE BEING SUBSTANTIALLY LARGER IN DIAMETER THAN SAID THROUGH BORE IN SAID FORM ELEMENT; A THREADED SHAFT RECEIVED WITHIN SAID THREADED BORE, AND HAVING A LENGTH SUBSTANTIALLY GREATER THAN THAT OF SAID BODY; A HEAD MOUNTED FOR UNIVERSAL SWIVEL MOVEMENT ON THE UPPER END OF SAID SHAFT; AND MEANS ON THE LOWER ENDS OF SAID BODY AND SAID SHAFT DEFINING WRENCH-ENGAGEMENT SURFACES. 